1. Field of the Invention
The present invention relates to a silver halide color photographic light-sensitive material, and more particularly to a silver halide color photographic light-sensitive material which contains silver halide emulsions introducing a number of dislocation lines and also contains a novel yellow coupler, which has a high sensitivity and excels in processed color image stability and pressure resistance.
2. Description of the Related Art
There is a demand for a silver halide color photographic light-sensitive material (hereinafter called "light-sensitive material"), particularly one for photography use, which has a high sensitivity and excels in graininess, color reproduction and sharpness, the photographic properties of which change but a little during storage, and which excels in processed image stability.
Generally used as yellow couplers for forming color photographic images are a benzoylacetoanilide type coupler having active methylene (methine) groups, and a pivaloylacetoanilide type coupler, as is described in T. H. James "The Theory of the Photographic Process," 4th edition, pp. 354-356. However, these couplers are very problematical. They can hardly be satisfactory in terms of coloring density, dye-forming speed, dye hue and dye stability. If a coupler having high coloring density or high dye-forming speed is used for imparting a high sensitivity, hue and dye stability are very low.
As well known in the art, most silver halide emulsions containing many dislocations will exhibit a high surface sensitivity if the surface of the silver halide grains are chemically sensitized to an appropriate degree. Couplers considered to fall within this category are Burton's emulsion and the halogen-converted emulsion, described in, for example, "Fundamentals of Photographic Engineering-Silver Salt Photography," ed. the Photograph Society of Japan, Corona Press, 1978, pp. 264 and 265.
Also known in the art is that a reduction-sensitized emulsion generally exhibits a high sensitivity, as is described in, for example, "Fundamentals of Photographic Engineering-Silver Salt Photography," ed. the Photograph Society of Japan, Corona Press, 1978, pp. 90, 91, and 253.
In view of the structure of the light-sensitive material, it is desirable in some cases that silver halide grains be tabular. For instance, tabular grains are advantageous in that the sharpness will increase if the grains are arranged on the side near incident light. This is because the tabular grains are orientated with their major surfaces located parallel to the support of the light-sensitive material, so that scattering light can hardly reach the side away from the incident light. Further, since tabular grains have a great surface area-to-volume ratio, a sensitizing dye can be adsorbed to the grains in a relatively large amount per unit area, whereby the amount of light absorbed into the grains increases, making the light-sensitive material highly sensitive. These facts are described in detail in, for example, JP-A-58-113927. ("JP-A" means Published Unexamined Japanese Patent Application.)
Generally, various pressures are applied to photographic light-sensitive materials coated with silver halide emulsions. For example, negative film for general photographic use is rolled into a cartridge, bent and pulled while being fed, frame by frame while being loaded into a camera.
Sheet-like film, such as light-sensitive materials for use in printing and X-ray sensitive materials for direct use in medicine, are handled directly by people, and is often bent or curved.
Any light-sensitive material receives a high pressure when it is cut or processed.
If various pressures are applied to a photographic light-sensitive material, they are exerted on the silver halide grains through the gelatin used as binder for the silver halide grains or the plastic film used as support. When pressures are exerted to the silver halide grains, changes occur in the photographic properties of the photographic light-sensitive material, as is known in the art, or as is reported in detail in, for example, K. B. Mather, J. Opt. Soc. Am., 38 1054 (1948), P. Faelens and P. de Smet, Sci. et Ind. Phot., 25, No. 5.178 (1954), P. Faelens, J. Phot. Sci., 2, 105 (1954).
In recent years, the requirements made of silver halide emulsions for photographic use have become more and more severe. For example, it is demanded that the emulsions have not only better photographic properties such as sensitivity and higher image qualities such as graininess and sharpness, but also greater toughness such as storage stability and pressure property. Obviously, however, an increase in sensitivity is accompanied by an increase in pressure marks. Hence, an emulsion is desired which has a high sensitivity and has less pressure marks. JP-A-63-220228 discloses silver halide grains which have improved exposure-illminance dependency, storage stability and pressure property. However, these grains are not sufficiently improved in terms of pressure marks due to the film scratching taking place within a camera or caused by claws.
The research of the inventors hereof has made it clear that fog generated when pressures are applied to the light-sensitive material is increased by absorbing a sensitizing dye onto the silver halide grains. This phenomenon was particularly remarkable in the case of large tabular grains having a great surface area-to-volume ratio. A sensitizing dye may be adsorbed to the silver halide grains at a high temperature (e.g., 50.degree. C. or more) in order to prevent desorption of the dye from the silver halide grains (particularly, at high humidity). This process will increase pressure marks. There is a method in which a sensitizing dye is adsorbed before chemical sensitization, in order to make the emulsion more sensitive. This method, however, will increase pressure marks, too.
The techniques of making silver halide emulsions more sensitive, described above, and the techniques of spectral sensitization, if employed in combination of the use of conventional yellow couplers, provide light-sensitive materials which have poor storage stability after exposed and developed and which do not have stable properties required of any practical light-sensitive material.